Embedded Phase Change Material Research Articles

Thermal performance augmentation of honeycomb metal matrix embedded phase change material in shell-tube latent heat storage unit

Due to the global warming challenge, there is a transition from the utilization of fossil fuels to harvesting new and renewable energy sources globally. Solar energy, being the infinite source with easy accessibility, leads the race among other allied sources. However intermittent nature of it demands an efficient thermal energy storage system. In the present experimental study, an innovative heat transfer augmentation technique i.e. aluminium honeycomb grill and fine mesh embedded in PCM is demonstrated. Both visualization of PCM melt fraction and capture of temperature contour complemented each other to identify the honeycomb version (HC-LHSU) as substantially better (43 % improvement in charge period) than the base model (BM-LHSU). On the other side, due to fine pores (porosity = 95 %), the fine meshmodel (FM-LHSU) yielded poorer results than BM-LHSU. Even the temperature gradient that exists during the charge or discharge period is gauged and recognized HC-LHSU as the best, followed by BM-LHSU and FM-LHSU. Since the onset of the phase transition zone reflects heat storage rate, the same is identified, and the charge period (sensible heat + latent heat) assessed to be 8000 s, 10000 s, and 12,000 s for HC-LHSU, BM-LHSU, and FM-LHSU, respectively. Further, an improvement in the average Nusselt number by 74 % and 67 % during the charge and discharge period respectively compared to the base model justified the honeycomb grill's role in augmenting the energy storage unit's performance.

Effect of conductive particles embedded phase change material on the productivity of a solar still in a controlled environment

A solar still’s performance using 3 different conductive particles embedded in the phase change material (PCM) has been studied. The conductive particles involved are aluminium scrap (Al), aluminium oxide (Al2O3) nano powder and copper (Cu) nano powder, whereas the PCM is paraffin wax. Four similar solar still models were built with different PCMs, differentiated as Model A, B, C, and D, filled with Al scrap-PCM, Al2O3 nano-PCM, Cu nano-PCM, and Al2O3 + Cu-nano PCM combinations, respectively. The productivity of the solar stills for Models A, B, C, and D are 1.93, 2.15, 1.93, and 2.20 kg/kJ.m2 respectively. It was concluded that Al2O3 + Cu-nano PCM is the most efficient PCM-conductive particle combination and Cu nano powder can be replaced by aluminium scrap as an economical alternative.

Experimental results of embedded phase change material capsules for increasing the performance of a wrapped heat pump water heater

To enhance the capacity of heat pump water heaters (HPWHs), high energy density phase change material (PCM) was used in two experimentally tested HPWH prototypes. Preliminary findings showed that in the PCM, stored thermal potential energy could be effectively converted into sensible heat in the water over a slight temperature difference, with the goal of increasing the capacity of hot water above a desired cut-off temperature. This exchange of energy results in an increased amount of hot water necessary for mixing at the location utilized by the consumer. It was also found that for a wrapped HPWH, there was an average increase of 27.7% in the capacity when 7.6 L of novel PCM filled spherical capsules were added to a 22.7 L tank downstream of the HPWH. In the second design (Beta), PCM capsules were immersed into the tank with a cylindrical geometry, and the UEF was increased by 5.5% over the baseline HPWH test result. As for the Beta design, heat loss was reduced significantly compared to a typical HPWH and the Alpha design. Food-grade PCMs were selected as appropriate. The novel encapsulation design increased the effective conductivity inside the capsule by adding metal fins.

Tetrapods based engineering of organic phase change material for thermal energy storage

Phase change materials (PCM) are largely assessed on their ability towards energy storage and their enthalpy efficiency of discharging the stored energy. Nevertheless, their applications are limited by the low thermal conductivity behaviour, despite their tunable transition temperature abilities. The present work demonstrates a novel concept to develop and explore PCM composite by embedding two unique zinc oxide tetrapod classes to engineer the heat transfer mechanism for potential utilization in thermal energy storage. Tetrapods embedded phase change material (TPCM) composite displayed up to 94% enhancement in thermal conductivity without compromising melting enthalpy. TPCM composite with high thermal conductivity, high heat capacity, broad photo-absorptivity, improved stability in isothermal conditions, and long thermal cycles offer attractive solutions for effective thermal energy storage, efficient solar energy harnessing, and thermal management. With demonstrated abilities, the developed TPCM composite material could play a significant role in the progress of renewable energy needs in future.

Preface

The 2022 International Conference on Energy and Power Engineering (EPE 2022) was successfully held in Sanya, China on October 21st-23rd, 2022 (virtual conference). EPE 2022 provided an international platform for experts, scholars, and engineers to share professional experience and exchange new ideas, and to explore the key challenges and research directions facing the development of these fields, as well as promoted the development and integration of related disciplines.We had the honor of having invited Prof. Mohan Kolhe from University of Agder, Norway to serve as our Conference Chair. The conference was composed of keynote speeches, oral presentations, and online Q&A discussion, bringing together over 150 delegates from all over the world. Firstly, keynote speakers were each allocated 30-45 minutes to hold their speeches. Then in the next part, oral presentations, the excellent papers we had selected were presented by their authors one by one.During the conference, two distinguished professors were invited to address their keynote speeches. For a start, Prof. Kamil ARSLAN from Karabük University, Turkey made a report on the title Magnetohydrodynamics (MHD). Fluid flow under the magnetic field effect is stated as Magnetohydrodynamic (MHD) phenomenon which is the field that examines the dynamic behavior of electrically conductive fluids. He showed us the background, the researches and then his study on Magnetohydrodynamics (MHD). And then, Prof. Santhanam Harikrishnan from Kings Engineering College, India delivered a speech on Thermal Characteristics of Nanomaterials Embedded Phase Change Materials (NePCMs). He introduced that phase change materials (PCMs) employed in LTES for larger-scale applications are limited due to their low thermal conductivities and then nanomaterials are suspended to accelerate the energy storage/release rate capabilities, which leads to the improvement of the thermal properties of the pure PCMs. Their brilliant keynote speeches had sparked heated discussion in the conference. And every participant praised this conference for disseminating useful and insightful knowledge.List of Committee member are available in this pdf.

Effect of latent heat storage on thermal comfort and energy consumption in lightweight earth-based housings

Embedding PCMs in building materials has attracted great interest due to their ability to store thermal energy. Storage of heat and cold is an efficient way to save energy. Considering a lightweight earth-based material, mixture of soil with a high straw content, the present work aims to improve its thermal properties by using phase change materials (PCM). In this investigation, a laboratory experimental campaign and subsequent numerical analysis were carried out to examine the impact of incorporating PCM within the lightweight earth-based material. Materials' hygro-thermal properties (thermal conductivity, specific heat capacity and water vapor permeability), determined experimentally in laboratory, have been considered to calculate energy consumption and occupant's comfort in a typical single-family housing. Experimental results showed an improvement of the lightweight earth-based material thermal conductivity and specific heat capacity, as well as a slight reduction in its water vapor permeability depending on the PCM content. These modifications in the lightweight earth-based material properties lead to predict an improvement of occupants' thermal comfort and a reduction of energy consumption in buildings that will be made with such a material. Finally, this study underlined the existence of an optimal phase change temperature regarding climate in which the building evolves.

Experimental Investigations of the Effect of Ultrasonic Waves on the Thermal Performance of Nanoparticles Embedded Phase Change Material

Experimental Investigations of the Effect of Ultrasonic Waves on the Thermal Performance of Nanoparticles Embedded Phase Change Material

Three-dimensional heat transfer studies of glazed and unglazed Photovoltaic/Thermal systems embedded with phase change materials

• The photovoltaic/thermal modules assembled with PCMs were numerically analyzed. • The assembled photovoltaic/thermal structures were evaluated from the energetic and exergetic views. • Embedding PCMs in photovoltaic/thermal modules are benefit for the CO 2 mitigation. In this study, a three-dimensional numerical simulation is carried out to implement a comparative analysis between the glazed and unglazed photovoltaic/thermal (PV/T) integrated structures incorporated without or with phase change materials (PCMs) at distinct locations using water as a coolant. Accordingly, six glazed and unglazed PV/T or PV/T-PCM configurations are designed through burying the water pipes within the PCM and positioning an additional PCM layer with different melting temperature from the upper one. The performance of the proposed layouts is evaluated and compared from the energy and exergy points of view. The effect of coolant flow rate is also evaluated in both the laminar and turbulent regions along with assessing the environmental impact of the proposed modules to analyze the daily CO 2 reduction. The results show that burying the water pipes inside the PCM beneath the PV/T module yields a significant improvement of the overall performance. Also, the electrical energy generated from unglazed modules is somewhat higher than that generated from the glazed modules, however the daily thermal energy output for the glazed modules is marginally higher than that generated from unglazed layouts having the same layer arrangement. Among the proposed structures, the glazed and unglazed PV/T modules integrated with dual PCMs achieve the highest daily average energetic and exergetic efficiencies, respectively.

Year-long energy analysis of building brick filled with phase change materials

Recently, embedding phase change materials (PCMs) within building walls have attracted significant attention as an energy-saving technique. However, year-long analysis requires further investigation. Therefore, this study proposes two different models, that is, simulated and validated with experimental results using data from the literature. Analysis for one year is conducted to estimate the energy-saving using PCM in building brick. Energy assessment of a common brick filled with PCM is investigated. The effect of using different PCM types and arrangements is evaluated. The results show that integrating PCM to the block enhances the thermal properties of building materials by modifying the thermal storage ability of the wall materials and decreasing and shifting the peak load on the building. Using n-Eicosane as a PCM shows the lowest maximum temperature of 37.86 °C with the peak indoor heat flux decreased by 29% and shifted by 9.28%. Moreover, one-year simulations reduce the average indoor surface temperature by 1.5% using PCM with an 8% reduction in total energy transfer. Additionally, n-Eicosane gives the highest energy saving of 18.69% compared to other types of PCM and configurations. Also, results show that horizontal wall orientation received the highest value of heat gain during the day.

Silver/Polypyrrole-Functionalized Polyurethane Foam Embedded Phase Change Materials for Thermal Energy Harvesting.

Conversion of solar energy into thermal energy stored in phase change materials (PCMs) can effectively relieve the energy dilemma and improve energy utilization efficiency. However, facile fabrication of form-stable PCMs (FSPCMs) to achieve simultaneously energetic solar–thermal, conversion and storage remains a formidable challenge. Herein, we report a desirable solar–thermal energy conversion and storage system that utilizes paraffin (PW) as energy-storage units, the silver/polypyrrole-functionalized polyurethane (PU) foam as the cage and energy conversion platform to restrain the fluidity of the melting paraffin and achieve high solar–thermal energy conversion efficiency (93.7%) simultaneously. The obtained FSPCMs possess high thermal energy storage density (187.4 J/g) and an excellent leak-proof property. In addition, 200 accelerated solar–thermal energy conversion-cycling tests demonstrated that the resultant FSPCMs had excellent cycling durability and reversible solar–thermal energy conversion ability, which offered a potential possibility in the field of solar energy utilization technology.

Machine-learning assisted optimization strategies for phase change materials embedded within electronic packages

Leveraging the latent heat of phase change materials (PCMs) can reduce the peak temperatures and transient variations in temperature in electronic devices. But as the power levels increase, the thermal conduction pathway from the heat source to the heat sink limits the effectiveness of these systems. In this work, we evaluate embedding the PCM within the silicon device layer of an electronic device to minimize the thermal resistance between the source and the PCM to minimize this thermal resistance and enhance the thermal performance of the device. The geometry and material properties of the embedded PCM regions are optimized using a combination of parametric and machine learning algorithms. For a fixed geometry, considering commercially available materials, Solder 174 significantly outperforms other organic and metallic PCMs. Also with a fixed geometry, the optimal melting points to minimize the peak temperature is higher than the optimal melting point to minimize the amplitude of the transient temperature oscillation, and both optima increase with increasing heater power. Extending beyond conventional optimization strategies, genetic algorithms and particle swarm optimization with and without neural network surrogate models are used to enable optimization of many geometric and material properties. For the test case evaluated, the optimized geometries and properties are similar between all ML-assisted algorithms, but the computational time depends on the technique. Ultimately, the optimized design with embedded phase change materials reduces the maximum temperature rise by 19% and the fluctuations by up to 88% compared to devices without PCM.

Hierarchically porous wood-derived carbon scaffold embedded phase change materials for integrated thermal energy management, electromagnetic interference shielding and multifunctional application

The increasing growth of powerful and sophisticated electronic devices have an urgent need for excellent heat dissipation and electromagnetic interference shielding materials. However, few studies are focusing on one material with these properties. In this work, a novel hierarchically porous wood-derived carbon scaffold embedded phase change material was prepared via facile pyrolysis and vacuum infiltration process. Notably, the raw wood was pretreated by a delignification strategy, which makes great contributions to forming a hierarchically porous network and expanding the internal area after pyrolyzing. The results demonstrate that the honeycomb-like structure of the wood carbon scaffold was well maintained after calcination, which can provide a great number of channels for energy transmission and multi-reflection of electromagnetic waves. Moreover, the paraffin wax component as phase change material not only stores and releases numerous energies during the melting and solidification processes, but also endows the composite outstanding self-cleaning function. The present composite shows excellent energy storage property (the latent heat of 122.25 J/g) and satisfied electromagnetic interference shielding performance (average shielding effectiveness of 24.4 dB). Therefore, the synthesized porous wood carbon scaffold/paraffin wax composite has great potential in multifunctional, environmentally friendly thermal energy management and electromagnetic interference shielding applications.

A Study of Hot Climate Low-Cost Low-Energy Eco-Friendly Building Envelope with Embedded Phase Change Material

The generation and use of energy are significant contributors to CO2 emissions. Globally, approximately 30% to 40% of all energy consumption can be directly or indirectly linked to buildings. Nearly half of energy usage in buildings is linked to maintaining the thermal comfort of the inhabitants. Therefore, finding solutions that are not only technically but also economically feasible is of utmost importance. Though much research has been conducted to address this issue, most solutions are still costly for developing countries to implement practically. This study endeavors to find a less expensive yet straightforward methodology to achieve thermal comfort while conserving energy. This study takes a broader view of multiple habitat-related CO2 emission issues in developing regions and describes a hybrid solution to address them. New technologies and innovative concepts are being globally examined to benefit from the considerable potential of PCMs and their role in thermal energy storage (TES) applications for buildings. The current study numerically investigates the thermal response of a hybrid building envelope consisting of PCM and local organic waste materials for low-cost low-energy buildings. The local organic waste materials used are those whose disposal is usually done by burning, resulting in an immense amount of greenhouse gases. In the first phase, different waste materials are characterized to determine their thermophysical properties. In the second phase, a low-cost, commonly available PCM calcium chloride hexahydrate, CaCl2·6H2O, is integrated with a brick and corn husk wall to enhance the thermal storage in the building envelope to minimize energy consumption. Temperature distribution plots are primarily used for analysis. The results show a marked improvement in thermal comfort by maintaining a maximum indoor temperature of 27 °C when construction is performed with a 6% corn husk composite material embedded with the PCM, while under similar conditions, the standard brick construction maintained a 31 °C indoor temperature. It is concluded that the integration of the PCM layer with the corn husk wall provides an adequate solution for low-cost and low-energy buildings.

High thermal conductivity and high energy density compatible latent heat thermal energy storage enabled by porous AlN ceramics composites

Ceramics embedded phase change materials (PCMs) composites are promising candidates for high-temperature thermal energy storage due to good chemical stability and high thermal shock resistance. However, the energy storage rate is severely restricted by the low thermal conductivity of composites. Here, we successfully achieve high thermal conductivity and high energy density compatible thermal energy storage based on porous AlN-eutectic NaCl/LiNO3 composites. Designed composites possess a high thermal conductivity ranging from 31.8 to 52.63 W/m-K benefiting from continuous thermal transport channels of densified AlN skeletons. Meanwhile, the phase change enthalpy reaches 140 to 186 kJ/kg since about up to 92% of pores are filled with PCMs. Further decorating AlN skeletons with TiN nanoparticles can significantly increase the solar absorptance from 70% to 90%, enabling proposed composites to be applicable for direct solar thermal energy storage as well. This work provides new routes to achieve high thermal conductivity and energy density compatible thermal energy storage via porous AlN ceramics-based phase change composites.

Dynamic state-space model and performance analysis for solar active walls embedded phase change material

Abstract Building-based active envelopes play an important role to reduce active heating supplies. Several techniques are developed to enhance the energy performances of active building envelopes; meanwhile, numerous numerical and mathematical models are also developed to conduct the performance analysis of these techniques. In this paper, we propose a state-space model for solar active wall-based Phase Change Materials (PCM). The advantage of this method remains in its simplicity to provide details of internal nodes and input/output parameters. The low-cost calculation is a supplementary advantage versus a heavy numerical method. The proposed numerical model is applied for a multi-layer wall with PCM Wallboards (PCMW) embedded between indoor and outdoor environments. The results show the ability of the state-space model to estimate the thermal behavior of the system, as well as the thermal characteristics of embedding PCM in the internal face of the wall. It significantly contributes to stabilize the indoor temperature and to ensure the thermal comfort.

Impacts of magnetic field and hybrid nanoparticles in the heat transfer fluid on the thermal performance of phase change material installed energy storage system and predictive modeling with artificial neural networks

In this study, impacts of magnetic field and hybrid nanoparticle addition in the heat transfer fluid are numerically studied for a thermo-fluid system with embedded phase change material during charging mode of operation by using finite element method. The magnetic field is uniform in radial direction while different strengths are considered in various domains of the computational model. Parametric numerical investigation is performed for various values of Hartmann numbers (Ha1 and Ha2 between 0 and 40), solid nanoparticle volume fraction of hybrid particles (between 0 and 0.02) and porosity of the medium (between 0.40 and 0.60). It was observed that the charging time is reduced with the imposed magnetic field while fast phase transitions occur near the walls. Dynamic characteristic of liquid fraction curves are changed with the magnetic field effects, nanoparticle inclusion and porosity of the medium. A reduction up to 40% is achieved in the charging time when the magnetic field strength of the phase change material domain is increased to Ha=40. The improved thermal transport features with hybrid nanoparticle inclusion in the heat transfer fluid is obtained. As water and nanofluid at the highest solid volume fractions are compared, 18.5%, 17.8% and 15% of reduction in the charging time is attained when cases with various magnetic field strength combinations at (Ha1, Ha2)=(40,40), (0, 40) and (40,0) are considered. Finally, estimation of charging time for different magnetic field strengths of domains and solid volume fractions of the hybrid particles is performed by using the artificial neural network based modeling approach which delivers fast and accurate results.

A comprehensive study on thermal storage characteristics of nano-CeO2 embedded phase change material and its influence on the performance of evacuated tube solar water heater

Abstract This work examines the enhancement in thermal storage properties of the new kind of nano-embedded phase change materials (NEPCMs), which were prepared by diffusing CeO2 nanoparticles in three mass fractions such as 0.5%, 1.0%, and 2.0% in paraffin, respectively. The synthesized NEPCMs had experimentally tested with field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC), thermal properties analyzer, and Fourier transform infrared spectrometer (FT-IR). Subsequently, the performance of water-in-glass evacuated tube solar water heater was investigated, under the influence of paraffin and NEPCMs. The experiments were conducted in five cases, namely, without PCM, with paraffin as PCM, and the last three cases with three different mass fractions of CeO2 nanoparticles in NEPCMs under real-time solar exposure between 6.00 a.m. and 6.00 p.m. The performance was studied using the first law and the second law efficiencies. It is exhibited that the thermal storage characteristics of the paraffin have been enriched significantly with the dissemination of CeO2 nanoparticles. Likewise, the experimentations with solar water heater ascertained that the assimilation of paraffin and NEPCMs enhanced the first law and the second law efficiencies of the system, impressively. Furthermore, the NEPCM containing 1.0% of CeO2 nanoparticles has found to be the precise combination.

Developing NaAc∙3H2O-based composite phase change material using glycine as temperature regulator and expanded graphite as supporting material for use in floor radiant heating

Floor radiant heating embedded phase change materials (PCMs) are a prospective field owing to its highly efficient energy-saving effect and comfortable thermal environment. In this work, using a non-eutectic mixture comprised of NaAc∙3H2O (main PCM) and glycine (temperature regulator) as PCM, and expanded graphite (EG) as supporting material, a novel composite PCM with high thermal performance used in the heat exchanger for the floor radiant heating was developed. The composition of the composite PCM was optimized, and its properties were studied. The results showed that the mixture containing 12% glycine was favorable due to its suitable phase change temperature (48.62 °C) and high phase change enthalpy (258.5 kJ·kg−1). The addition of 12% EG into the mixture could enhance thermal conductivity and prevent leakage of the mixture simultaneously. The resulting composite PCM melted at 47.14 °C with phase change enthalpy of 214.7 kJ·kg−1, supercooling degree of 1.49 °C and thermal conductivity of 6.400 W m−1 K−1. The composite PCM also presented a good thermal reliability. Hence, the as-prepared composite PCM would be of great promise for use in the heat exchanger for the floor radiant heating. Besides, the present work is expected to provide a new pathway for exploring new types of PCMs.

Comparative study of solar hot air heating systems with phase change materials in plateau areas

Rich solar energy resources in plateau areas of Western China are suitable for local heating. However, common solar heating systems face the potential hazard and maintenance difficulties caused by climatic conditions. In this paper, the solar hot air heating system using the air medium evacuated tube collectors (ETCs) with embedding phase change materials (PCM) was discussed, which can be a good solution in plateau areas. The whole system model was built in TRNSYS software and validated with practical data. Then the comparative study was conducted to evaluate the energy-efficiency performance and feasibility of six kinds of solar heating systems, which also involved the fully electric heating, based on the three thermal types of buildings in Lhasa. It was concluded that the solar hot air heating system is the most suitable application in plateau areas, which shifts more solar energy to night time heating and requires less maintenance. Furthermore, the influence of parameters on the system performance was also investigated, such as collector area, buffer tank volume and electric power. This study will help the design and application of solar hot air heating system with PCM in plateau areas for winter heating.

Enhancement of power generation of thermoelectric generator using phase change material

This paper demonstrates a thermoelectric generator (TEG) that embeds phase change material (PCM) for waste heat energy harvesting. In this TEG module, a volume of molten carbonate salt is encapsulated in a cuboid polydimethylsiloxane (PDMS) body. In order to study the effect of embedded PCM on the TEG performance, we compared the performance of TEGs with and without PCM. The results show that a higher output voltage and a longer energy harvesting time can be reached in TEG with PCM in compared with the corresponding values in the TEG without PCM once the heat source stops supplying heat. Especially, the relative increase of the total electricity by adopting the PCM is as large as 25%. Our work proposes an effective and feasible way to enhance the performance of the TEG system by application of the PCM.